Fair Value of Financial Instruments - Schedule of Measured at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Earnout liability	$ 0	$ 14,547	$ 0
Recurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Due from related parties related to share based payment awards	15,797	14,339
Investments	17,610	23,520
Employer compensation liability related to share based payment awards	15,797	14,339
Earnout liability		11,958
Recurring basis | Interest Rate Cap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate caps	1,758
Recurring basis | SEVN
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	17,610	23,520
Recurring basis | Joint Venture
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	11,134
Recurring basis | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Due from related parties related to share based payment awards	15,797	14,339
Employer compensation liability related to share based payment awards	15,797	14,339
Earnout liability	0	0
Recurring basis | Level 1 | Interest Rate Cap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate caps	0
Recurring basis | Level 1 | SEVN
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	17,610	23,520
Recurring basis | Level 1 | MF Fund VII
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0
Recurring basis | Level 1 | Joint Venture
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0
Recurring basis | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Due from related parties related to share based payment awards	0	0
Employer compensation liability related to share based payment awards	0	0
Earnout liability	0	0
Recurring basis | Level 2 | Interest Rate Cap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate caps	1,758
Recurring basis | Level 2 | SEVN
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	0
Recurring basis | Level 2 | MF Fund VII
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0
Recurring basis | Level 2 | Joint Venture
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0
Recurring basis | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Due from related parties related to share based payment awards	0	0
Employer compensation liability related to share based payment awards	0	0
Earnout liability	3,639	11,958
Recurring basis | Level 3 | Interest Rate Cap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest rate caps	0
Recurring basis | Level 3 | SEVN
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0	$ 0
Recurring basis | Level 3 | MF Fund VII
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	3,156
Recurring basis | Level 3 | Joint Venture
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	$ 11,134